Carburetor

ABSTRACT

A multibarrel carburetor for an internal combustion engine having an auxiliary carburetor to provide fuel and air to idle, to the intake manifold, when the main throttles are closed at engine-idling speed. The auxiliary carburetor is provided with a throttle valve under the control of a pair of motors and has outlets for conducting idling fuel into a pair of throats of the carburetor. One of the motors is operated by manifold suction, when one of the valves of the carburetor is opened, to open the valve of the auxiliary carburetor. The other motor is operated when the valves of the carburetor are closed and the speed of the engine is above a preselected amount to close the throttle of the auxiliary carburetor.

United States Patent Primary Examiner-Tim R. Miles ABSTRACT: Amultibarrel carburetor for an internal combustion engine having anauxiliary carburetor to provide fuel and air to idle, to the intakemanifold, when the main throttles are closed at engine-idling speed. Theauxiliary carburetor is provided with a throttle valve under the controlof a pair of motors and has outlets for conducting idling fuel into apair of throats of the carburetor. One of the motors is operated bymanifold suction, when one of the valves of the carburetor is opened, toopen the valve of the auxiliary carburetor. The other motor is operatedwhen the valves of the carburetor are closed and the speed of the engineis above a preselected amount, to close the throttle of the auxiliarycarburetor.

caunuuarou The objects of the invention are as stated in the abstract,the mixing of the air and fuel to idle in a very small auxiliarycarburetor and dividing such mixed fuel and air to flow into two throatsof a multiple throat carburetor.

The use of the suction from the port on the upstream side of the highedge of the butterfly usually used to operate the enginesuction-operated spark advance to operate the throttle of the littlecarburetor to open it automatically when the main throttles are crackedand full manifold suction is developed from said spark advance port.

The use of an engine speed sensor and a throttle closed sensor tocontrol a motor to close the throttle in the little carburetor on closedthrottle decelerations above a selected engine speed to reduce totalsmog-producing elements in the exhaust on such decelerations to provideoutside adjustment from the fuel flowing to the little carburetor fromthe main carburetor bowl for adjustment purposes.

Other objects will be more particularly pointed out in the accompanyingspecification and claims.

I have illustrated my invention by way of example in the accompanyingdrawings, in which:

1 16. 1 is a plan view partly cutaway showing one form of the invention.

F16. 2 is a side elevation partly cut away and partly diagrammaticshowing the invention shown in FIG. 1.

In these figures I haveshown a four barrel carburetor of conventionaldesign with a smog control for opening the sandwich between thecarburetor 9 and the engine 10. The carburetor 9 has two primary barrels12a and 13a on the lower half (as shown) and two secondary barrels 20and 21 in the upper half (as shown). Usually the throttles on thesecondary barrels open as the primary throttles are almost open bymechanical and/or spring means of conventional nature not shown here asthey are show in US. Pat. No. 2,722,207 to J.O. Sarto, entitled MultipleStage carburetor, dated Nov. 1955.

Referring to H0. 1 and FIG. 2, thick sandwich 11 has two primary throats12a and 13a aligned with the primary throats or barrels 12 and 13 ofcarburetor 9. These throats 12 and 13 have throttle valves 17 and 18mounted on shaft 24 with throttle control arm 25. Link 22 connects arm25 and unit 23 for controlled motion of throttle butterflies in throats21 and 20 by unit 23 as shown in said Sarto reference.

Throttle 30 in small carburetor 35 ismounted on shaft 31 and controlledby arm 32. Suction motor 40, through shaft 41 can move throttle 30 fromthe idle speed position, possibly as shown, to full open when manifoldsuction is present in port 42 and lines 43 and 45, andtosuction-operated motor 40, as when the edge 18a of throttle 18 movesabove port 42 as when substantially above idle operation. This suctionfrom port 42 through tube 450 will also actuate the suction operatedspark advance motor 50 to advance breaker plate 52 by arm 51 in theusual manner.

Suction-operated motor 60 is supplied with suction from intake manifoldby tube 61 to valve V1 which is open when the throttle is closed, thenby line 62 to valve V2 which is open above a predetermined engine speedso that on closed throttle deceleration above a selected engine speedsuction will flow from intake manifold 8 past said valves and into line63 to suction motor 60 to pull rod 64 to the right; as viewed in FIG. 2,to close throttle 30 in small carburetor 35 to shut off the air to idleas well as the fuel to idle. Carburetor 35 feeds air to idle and fuel toidle to the engine through elbow 70 attached to sandwich 11 and then bypassages 71, 73 and 72 to tubes 74 and 75 in passages 12a and 13a ofsandwich 11 respectively. The ends 74a and 750 are turned down towardengine 10 and deliver the air and fuel to idle at high velocity near thecenter of the primary throats 12a and 13a of sandwich 11. to providebetter fiiel and air mixing at idle, and low power cruises at variousspeeds. Fuel to idle is picked up by tube 80 which may have adjustableneedle 81 leading to the orifice near the bottom of the float chamber9a.

Adjustment screw 84 may adjust the air bleed through port 85 to get thecorrect rich fuel and air ratio going through tube 86 to valve 87. Valve87 has adjustable needle valve 88 to adjust the rich fuel and air flowfrom tube 86 to fuel jet tube 59 above venturi 90. Adjustment screws 91on motor 40 and 92 on motor 60 adjust the primary tension on the springsin each motor to provide an adjustment of the idle speed by adjustingthe position of throttle 30 in carburetor 35 when idling (and there isno suction in line 45 or line 63) to get the desired warm engine idlespeed.

The choke shaft can have choke valves 101 and 102 mounted thereon andoperated by arm 103. Arm 103 is connected by link 104 to bell crank 105.Link 106 connects bell crank to arm 107 that is on shaft 108. Chokevalve l09is on shaft 108 so that the motion of choke shaft 100 by rod110 and thermostat T or manual means (not shown) will choke carburetor35 by choke valve 109 when shaft 100 is moved to the choke position aswhenthe engine 10 is cold to choke the primary throats by choke valves10] and 102.

In operation when idling the throttles 17 and 18 are closed and usualidle fuel port below the throttles is not needed or shown. The air toidle enters past choke valve 109, picks up fuel from nozzle 89 pastventuri 90, past throttle 30 which adjusts the idle speed and isdelivered to the intake manifold 8 from primary thioats 12a and 13a insandwich 11 by curved tubes 74a and 75a respectively for improved mixingof the fuel and air to idle. As the throttles 17 and 18 are opened,suction from port 42 opens valve 30 by motor 40 to help the transition.Further power is provided by opening primary throttles 1.7 and 18 untilsecondary throttles in the throats above passages 20 and 21 are openedfor full power from all five barrels, including carburetor 35. Ondeceleration at closed throttle the butterflies in the primary andsecondary passages are closed and suction flows through line 63 to motor60 to close throttle 30 in carburetor 35 to close off such air and fuelfrom carburetor 35. When the throttles l7 and 18 are opened for powervalve V1 will close allowing throttle 30 to open to idle or widerposition by suction from port 42 with open throttle 18 which willoperate motor 40 to open valve 30 by suction from port 42.

As the throttle is left closed .on a deceleration and the engine speeddrops below that sensed by the actuator for valve V2, V2 will close toshut off the suction that closed valve 30 on the deceleration and itwill assume the position shown to reestablish engine idle before theengine stalls.

While I have shown this invention applied to a four barrel carburetor,it can also be applied to a multiple barrel carburetor of two or threebarrels, or even to a single barrel carburetor where a small carburetoris used for an idle fuel and airmixing device with a throat of aboutone-half the diameterof either of the main throat diameters foradmitting the fuel and air to idle and some of the air and fuel for lowspeed cruises.

The air that enters the small idling carburetor may be heated by anexhaust or hot water heat exchanger and flow through line 121 tocarburetor 35 so as to heat the air to idle much hotter than the airentering the main throats 12 and 13 at full power operation. This extraheat to the idle carburetor may result in better mixing of the fuel andair, better distribution between cylinders of a 'multicylinder engine onwhich such multibarrel carburetors are used and still not cut down onthe volumetric efficiency and power at full throttle. If the small idlecarburetor is used on a single barrel carburetor, the throat and venturimay be still further reduced to have about the same breathing capacityproportionally to the single main throat that it has to the breathingcapacity of the two primary throats of the multijet carburetor, asshown. I have illustrated my invention in these various forms; however,many other variations may be possible within the scope of thisinvention.

Iclaim:

1. A carburetor comprising a plurality of main throats each having athrottle valve therein and an outlet for supplying a combustible mixtureto an intake mainfold of an internal combustion engine for idling power,an auxiliary carburetor comprising a throat having a throttle valvetherein and an outlet for supplying a combustible mixture to the enginefor idling power, conduit means connecting the outlet of the auxiliarycarburetor into the outlets of at least a pair of outlets of the mainthroats adjacent the ends thereof, means for closing the throttle valveof the auxiliary carburetor when the throttle valves in the throats ofsaid at least one pair of outlets are closed and the speed of the engineis Above a predetermined amount, and means for partially opening thethrottle valve of the auxiliary carburetor for supplying a mixture foridling power when the throttle valves in the throats of said at leastone pair of outlets are closed and the speed of the engine is below saidpredetermined amount, wherein the means for closing the throttle valveof the auxiliary carburetor comprises a suction-operated motor, conduitmeans connected to said motor and intake manifold, valve means in saidconduit for opening and closing flow of fluid therethrough, and meansfor opening said valve means when the throttles of said at least onepair of outlets are ,closed and the speed of the engine is above saidpredetermined amount.

2. A carburetor as defined in claim 1 further including means for fullyopening the throttle valve of said auxiliary carburetor when thethrottle valves in the throats of said least one pair of outlets areslightly opened.

3. A carburetor as defined in claim 2 wherein said last mentioned meanscomprises a suction motor, a port extending through the wall of one ofsaid main throats adjacent the upstream side of one of saidlast-mentioned throttle valves when said throttle valve is closed, andconduit means connecting said port and said last-mentioned suctionmotor.

4. A carburetor as defined in claim 3 wherein the means for partiallyopening the throttle valve of the auxiliary carburetor comprises meansconnecting both suction motors to said lastmentioned valve, and springmeans in said motors for urging said last-mentioned valve into thepartially opened position.

1. A carburetor comprising a plurality of main throats each having athrottle valve therein and an outlet for supplying a combustible mixtureto an intake mainfold of an internal combustion engine for idling power,an auxiliary carburetor comprising a throat having a throttle valvetherein and an outlet for supplying a combustible mixture to the enginefor idling power, conduit means connecting the outlet of the auxiliarycarburetor into the outlets of at least a pair of outlets of the mainthroats adjacent the ends thereof, means for closing the throttle valveof the auxiliary carburetor when the throttle valves in the throats ofsaid at least one pair of outlets are closed and the speed of the engineis Above a predetermined amount, and means for partially opening thethrottle valve of the auxiliary carburetor for supplying a mixture foridling power when the throttle valves in the throats of said at leastone pair of outlets are closed and the speed of the engine is below saidpredetermined amount, wherein the means for closing the throttle valveof the auxiliary carburetor comprises a suction-operated motor, conduitmeans connected to said motor and intake manifold, valve means in saidconduit for opening and closing flow of fluid therethrough, and meansfor opening said valve means when the throttles of said at least onepair of outlets are closed and the speed of the engine is above saidpredetermined amount.
 2. A carburetor as defined in claim 1 furtherincluding means for fully opening the throttle valve of said auxiliarycarburetor when the throttle valves in the throats of said least onepair of outlets are slightly opened.
 3. A carburetor as defined in claim2 wherein said last mentioned means comprises a suction motor, a portextending through the wall of one of said main throats adjacent theupstream side of one of said last-mentioned throttle valves when saidthrottle valve is closed, and conduit means connecting said port andsaid last-mentioned suction motor.
 4. A carburetor as defined in claim 3wherein the means for partially opening the throttle valve of theauxiliary carburetor comprises means connecting both suction motors tosaid last-mentioned valve, and spring means in said motors for urgingsaid Last-mentioned valve into the partially opened position.